Surface acoustic wave element and communication device

Abstract

An IDT electrode ( 3 ) on a piezoelectric substrate ( 2 ) has an electrode including first metal layers ( 31 a, 31 b ) formed of titanium or a titanium alloy, or chromium or a chromium alloy and second metal layers ( 32 a, 32 b ) formed of aluminum or an aluminum alloy, copper or a copper alloy, or gold or a gold alloy, which are laminated alternately. The orientation degrees in the first metal layer ( 31 a ) that is closest to the surface of the piezoelectric substrate ( 2 ) in the first metal layers ( 31 a, 31 b ) and the second metal layer ( 32 a ) that is closest to the surface of the piezoelectric substrate ( 2 ) in the second metal layers ( 32 a, 32 b ) are higher than the orientation degrees in the upper metal layers. As compared with the prior art where the orientation degrees in the first metal layers ( 31 a, 31 b ) and the second metal layers ( 32 a, 32 b ) are not considered, the power handling capability of the IDT electrode ( 3 ) can be significantly improved.

1. A surface acoustic wave element comprising:
 a piezoelectric substrate; and 
 an IDT electrode formed on the piezoelectric substrate having an electrode formed with a plurality of first metal layers comprising titanium or a titanium alloy, or chromium or a chromium alloy, and at least one second metal layer comprising aluminum or a aluminum alloy, copper or a copper alloy, or gold or a gold alloy, the metal layers alternately laminated one by one, 
 wherein an orientation degree in a layer in the first metal layers that is closest to a surface of the piezoelectric substrate is higher than the orientation degree in a layer in the first metal layers that is apart from the surface of the piezoelectric substrate. 
 
   
   
     2. The surface acoustic wave element according to  claim 1 , wherein the surface acoustic wave element includes a plurality of the second metal layers, and the orientation degree in a layer in the second metal layers that is closest to a surface of the piezoelectric substrate is higher than the orientation degree in a layer in the second metal layers that is apart from the surface of the piezoelectric substrate. 
   
   
     3. The surface acoustic wave element according to  claim 1 , wherein the first metal layers comprise titanium or a titanium alloy, and the second metal layer comprises aluminum or an aluminum alloy. 
   
   
     4. The surface acoustic wave element according to  claim 3 , wherein the layer in the first metal layers that is closest to the surface of the piezoelectric substrate has a thickness of 30 to 80 Å. 
   
   
     5. A surface acoustic wave element comprising:
 a piezoelectric substrate; and 
 an IDT electrode formed on the piezoelectric substrate having an electrode formed with at least one first metal layer comprising titanium or a titanium alloy, or chromium or a chromium alloy, and a plurality of second metal layers comprising aluminum or an aluminum alloy, copper or a copper alloy, or gold or a gold alloy, the metal layers alternately laminated one by one, 
 wherein the orientation degree in a layer in the second metal layers that is closest to a surface of the piezoelectric substrate is higher than the orientation degree in a layer in the second metal layers that is apart from the surface of the piezoelectric substrate. 
 
   
   
     6. The surface acoustic wave element according to  claim 5 , wherein the first metal layer comprises titanium or a titanium alloy, and the second metal layers comprise aluminum or an aluminum alloy. 
   
   
     7. The surface acoustic wave element according to  claim 6 , where in a layer in the first metal layer that is closest to the surface of the piezoelectric substrate has a thickness of 30 to 80 Å. 
   
   
     8. The surface acoustic wave element according to  claim 1 , wherein the second metal layers include crystal grains formed continuously from a surface apart from a surface of the piezoelectric substrate to a surface close to the surface of the piezoelectric substrate. 
   
   
     9. The surface acoustic wave element according to  claim 8 , wherein crystal grains whose sizes are larger in the direction of a principal surface than in the thickness direction of the metal layer occupy the major part. 
   
   
     10. A communication device using the surface acoustic wave element according to  claim 1  as a duplexer. 
   
   
     11. A communication device using the surface acoustic wave element according to  claim 5  as a duplexer.